(yam) aSvaththam – that samsAram which is [like] a holy-fig [banyan] tree
Urdhva mUlam – having the root at the top
adhaS SAkham – having the well spread out branches at the bottom
avyayam – imperishable (due to continuous existence)
yasya chandhAmsi parNAni – having vEdha vAkyams (texts) as the leaves
prAhu: – is said (by vEdham)
tham – that tree
ya: vEdha – one who knows
sa: vEdhavith – he is the knower of vEdham.

bhagavAn spoke – samsAram which is [like] a holy-fig [banyan] tree which is having the root at the top and the well spread out branches at the bottom, which is imperishable (due to continuous existence), which is having vEdha vAkyams (texts) as the leaves. One who knows that tree which is said (by vEdham), is the knower of vEdham.

Rendering based on ALkoNdavilli gOvindhAchArya swAmy’s English translation of gIthA bhAshyam

The Blessed Lord continued :—

‘With root above and branches below, they speak of an Aśvattha Tree1 indestructible, of which the leaves are the Vedas. Whoso knows this knows the Vedas.’

Samsāra is emblematized as the Tree Aśvattha, with root above and branches below. Its indestructible or everlasting nature is declared in the Śrutis thus:

The Tree is said to have the root above, since the four-faced Brahmā (the Demiurge of the Brahmāṇḍa, or a mundane egg) is seated above the seven4 worlds. It is said to have branches below since on earth below, are all its denizens, man, animals, beasts, worms, insects, moths, plants etc.

It is said to be indestructible, (avyayam) or never-ending like a stream flowing for ever, or a Tree which cannot be felled, till the dawning of spiritual illumination which would wean one from (material) clingings.

Chhandāmsi= the Śrutis=the Vedas, which are said to be the Tree’s leaves, since the Tree of Samsara flourishes in proportion to the performance of Śruti-enjoined kāmya-karmas (or works performed with a view to obtain material pleasures). Such as are declared in:

Whoso has the knowledge of this aforesaid Tree is the knower of the Vedas, since the Vedas teach the way how to fell the Tree. He is called the knower of the Vedas, since a knowledge of the nature of this destruction-worthy Tree, is essential as giving the knowledge necessary for felling the same.